Modifying Vitamin Composition of Eggs: A Review

Egg vitamin composition is variable and dependant primarily on the vitamin content of the diet of laying and breeding hens. Vitamin A content of eggs responds slowly to dietary vitamin A changes whereas, riboflavin content of eggs responds rapidly to similar changes. Riboflavin reaches a natural maximum content in eggs, while the egg content of vitamin D, pantothenic acid, folacin, biotin, and vitamin B12 responds greatly to increases in the diet level of these vitamins. At one to two times the National Research Council diet requirement levels, transfer efficiency to the egg is very high for vitamin A; it is high for riboflavin, pantothenic acid, biotin, and vitamin B12; it is medium for vitamin D3 and vitamin E; and low for vitamin K1, thiamine, and folacin. This information can assist growers in formulating diets for laying and breeding hens that will enrich egg vitamin content. At the same time, growers can eliminate much of the variability that has been observed in egg vitamin composition.